//不同的子序列
//测试链接：https://leetcode.cn/problems/distinct-subsequences/
public class NumDistinct {
    public int numDistinct(String s, String t) {
        int m = t.length(), n = s.length();
        int[][] dp = new int[m + 1][n + 1];
        for (int j = 0; j <= n; j++)
            dp[0][j] = 1;
        for (int i = 1; i <= m; i++)
            for (int j = 1; j <= n; j++) {
                dp[i][j] = dp[i][j - 1];
                if (t.charAt(i - 1) == s.charAt(j - 1))
                    dp[i][j] += dp[i - 1][j - 1];
            }

        return dp[m][n];
    }
}
